// デバイス割り当て後処理
void
IrrlichtSimpleDevice::onAttach()
{
	if (useRender) {
		if (device) {
			IVideoDriver *driver = device->getVideoDriver();
			// 描画開始
			if (driver) {
				target = driver->createRenderTargetTexture(driver->getScreenSize());
				if (target) {
					driver->setRenderTarget(target);
				} else {
					error_log("failed to create rendertarget");
				}
			}
		}
	}
}